1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus.
2. Description of the Related Art
In an electrophotographic image forming apparatus, it is known that a plurality of kinds of chemical substances are discharged from an image forming apparatus during image forming. For example, as a representative of the discharged chemical substances, there is ozone generated when a photosensitive drum is charged, or toner dust generated during developing or fusing. In the related art, in order to not allow the generated chemical substances to be discharged outside the image forming apparatus, for example, a measure of providing a filter or the like is performed.
For example, in a volatile chemical substance collection device of an electronic apparatus disclosed in Japanese Patent Unexamined Publication No. 2009-282455, an electric field is generated in an atmosphere from an electric field generating collection member in an exhaust duct provided above a fuser unit, and volatile organic compounds (VOC) included in the atmosphere are drawn to the surface of the electronic field generating collection member by the operation of the electric field so as to be collected.
In an image forming apparatus disclosed in Japanese Patent Unexamined Publication No. 2011-180235, a duct which includes a take-in port for taking-in minute particles generated from a heat roller inside a fusing device is provided in the vicinity of the fusing device. An exhaust fan which generates a flow of air from the take-in port toward an outlet is provided in an expansion portion of the duct, and a first filter member is provided on the upstream side of the exhaust fan. The first filter member captures ultrafine particles (for example, siloxane) generated from a rubber layer configuring the fusing device. A shutter which closes a gap between the first filter member and the expansion portion is provided, and a control portion of the image forming apparatus switches a state where the shutter closes a first filter portion and a state where the shutter does not close the first filter portion according to a predetermined initial burst condition.
In an odor removing device of a multi-function image forming apparatus disclosed in Japanese Patent Unexamined Publication No. 2011-180283, a plurality of air passage portions for introducing air inside a housing are formed on a housing bottom portion. Each air passage portion is a cylindrical body in which an inner diameter of the upper portion side inside the housing is smaller than an inner diameter of the housing bottom portion, and an ozone decomposition filter including an ozone decomposition catalyst is disposed on an inner diameter surface of the cylindrical body. A waste liquid absorbing material is disposed on the bottom portion inside the housing, a deodorizing absorbent is disposed on an upper cover inside the housing, and an exhaust port of the air passing through a portion between the waste liquid absorbing material and the deodorizing absorbent is provided on the side surface of the housing.
However, in recent years, according to enhancement in consciousness with respect to worldwide environment protection, minute particles (for example, ultrafine particles (UFP) having a particle diameter less than or equal to 100 nm) different from ozone or the like occurring from an electrophotogrpahic image forming apparatus have become a problem.
As a structure which captures the ultrafine particles, for example, like the electronic apparatus disclosed in Japanese Patent Unexamined Publication No. 2009-282455, when the volatile chemical substance collection device which draws volatile organic compounds to the surface of the electric field generating collection member and collects the compounds is additionally provided, there is a problem in that the structure becomes complicated.
For example, as the image forming apparatus disclosed in Japanese Patent Unexamined Publication No. 2011-180235, when the structure in which the first filter member capable of capturing minute particles is provided on the upstream side of the exhaust fan and the exhaust gas permeates the first filter member is provided, the first filter member increases resistance when the air is transported, and thus, exhaust efficiency is decreased and the temperature inside the housing is increased. Accordingly, the output of the exhaust fan should be increased, and thus, there is a problem that noise is generated and running cost is increased.
For example, as the multi-function image forming apparatus disclosed in Japanese Patent Unexamined Publication No. 2011-180283, when the plurality of (for example, two in Japanese Patent Unexamined Publication No. 2011-180283) exclusive odor removing devices are additionally provided, the structure becomes complicated and, there is a problem that a cost of the apparatus is also increased.
The present invention is made for solving the above-described problems in the related art, and an object thereof is to provide an image forming apparatus which decreases amounts of emission of ultrafine particles and suppresses an increase of output of the exhaust fan by a simple structure.